Food stuffs such as coffee, nuts, fruits and jams etc. are vacuum packed in order to maintain freshness for delivery to the consumer. Obviously however, the products begin to loose freshness the moment the container is opened and the vacuum lost to the surrounding atmosphere which is normally humid to a substantial degree. Therefore, hermetic closures have been attempted but even then the capture of air at atmospheric pressure subjects the product to the permeation of dampness. On the contrary, the reestablishment of a partial vacuum would impose the depressurization known to be so beneficial in maintaining freshness, and to this end it is a general object of this invention to provide a closure that draws a vacuum upon a container to preserve the freshness of the product previously vacuum packed therein. Reference is made to my previous U.S. Pat. No. 4,083,468 entitled "VACUUMIZING CLOSURE FOR VACUUM PACK CONTAINERS" issued Apr. 11, 1978, involving a vacuumizing closure that substantially reduces atmospheric pressure within the container so as to draw moisture from the product stored therein, thereby eliminating the otherwise expected gradual but continuous permeation of moisture leading to staleness of the product.
The application to containers of the usual stoppers, plug-in and screw-in closures, tends to compress the interior rather than to depress the same, and thereby impresses the atmospheric humidity upon the product remaining therein. The greater the volume of remaining product the greater is the compressive and/or depressive effect, due to the smaller remaining container space to be filled by said atmosphere. However, the lesser the volume of remaining product the greater is the remaining container space inherently filled with atmospheric humidity to have its adverse effect upon the product. Therefore, as the product is depleted the remaining air space becomes proportionately greater and presents an increasing volume of air subject to removal. Accordingly, it is an object of this invention to provide an improved closure that initially occupies the chamber together with the product therein, and operable to pump atmospheric humidity therefrom.
Containers for food stuffs are not filled to their brim, but are filled to a level which constitutes a measured portion either by weight or by volume. In any case, the fill level is below the container rim, and it is from this level that a portion of the product will be taken at the first opening of said container. For example, when brewing coffee the product level will be approximately an inch below the container rim after withdrawing sufficient coffee to brew a large pot thereof; and it is this measurement which determines the depth to which the present closure penetrates and which determines the permissible depth and draw of the diaphragm. It is an object therefore, to maximize the closure occupancy to thereby maximize the depth and draw of the diaphragm. With this invention, the closure enters into the container to the level of product therein, preferably after a normal portion thereof has been removed, thereby maximizing the vacuum pump effect.
The resealing of containers such as metal cans is a problem once the hermetic seal of the integral lid is broken, as for example by complete removal of said lid. With the usual beaded can construction, the rolled and/or crimped bead of the can is left to present a circumferential rim of smooth uniform cross section, distorted to some extent perhaps by slight imperfection in manufacture and by bending during the can opening process. Accordingly, it is an object of this invention to reestablish a hermetic seal with the bead left remaining at the circumferential rim of the can, to seal with the inner and outer diameters of the bead.
The amount of partial vacuum drawn by this device is dependent upon the number of strokes applied to the diaphragm. Whereas my previously patented closure is limited to a single stroke, the present device is adapted to operate as a multi stroke pump, and to this end check valve means are provided at both the diaphragm and at the cover so as to establish a variable volume pump chamber therebetween. It is an object therefore to reciprocate the diaphragm relative to the cover that establishes the pump chamber, and in practice three to six strokes will draw a most effective and high vacuum as circumstances require. Further, it is now necessary to release said vacuum and to this end it is another object to provide a bleed means through the diaphragm and cover or into the canister as desired.
The type and shape of the container to be sealed and vacuumized can vary widely, and it is therefore an object of this invention to accommodate glass or ceramic jars as well as tins, and including all cross sections thereof such as square, rectangular, oval or any other shape than cylindrical. Accordingly, it is an object of this invention to provide a vacuum pump closure for at least two shapes of container, namely a cylindrical container and one that is other than cylindrical. Primarily, it is the perimeter seal which is to be established and maintained and to this end it is an object to provide one or more perimeter seals engageable with the rim or bead of the container, jar or can, and which draws more tightly into sealed engagement therewith as the vacuum is increased.
It is a general object of this invention to provide a Vacuumizing Pump Closure of the character hereinabove referred to that is simple and economical of manufacture, and a device that is inherently practical for the purpose intended of pumping a partial vacuum upon the remaining content of a canister or jar or can and any such vessel that has been opened and/or which requires closure, so as to establish a hermetic seal with the rim or bead at the otherwise opened end thereof, a feature of the invention being the simplicity of application which requires movement of an actuating lever, and removal which requires opening of a bleed valve.